How many SIMMs are needed ?
On 386 and 486 systems that use 30 pin modules, you must fill up a “bank” of SIMMs at one time. This usually means that 2 SIMMs are required for SX systems and 4 SIMMs are required for DX systems. (Check your manual or examine your board). Newer 486 systems that us 72 pin modules usually only require 1 SIMM. Pentium boards use 72 pin SIMMs which generally must be inserted two at a time. To upgrade your Pentium board from 16 to 32 megabyte, you’ll need to buy two 8mb SIMMs because one 16mb would not work.
